Study of the ferrofluid drying process for morphological and nanostructutal characterization

Abstract

A drying method suitable for the study of the morphological and structural properties of colloidal magnetic systems, including a contrast agent used in Magnetic Resonance Imaging (MRI) is described. We tested three alternative ferrofluid drying methods: drying at 70 • C in nitrogen atmosphere; drying in air at 70 • C; and drying by liophylization using an MRI marker in the form of a colloidal suspension (Endorem T M-Guebert). X-ray diffraction (XRD), and transmission electron microscopy (TEM) were applied to each characterization method. The XRD allowed the observation of the possible physical-chemical changes of the stabilizers and also Fe 3 O 4 present in the system. The morphology and nanoparticles size distribution was analyzed by TEM. Among the drying methods examined in this study, the liophylization has shown to be the more adequate one for the nanoparticles (Fe 3 O 4) morphological study and nanostructural characterization, because the structure of the nanoparticles was maintained the same as in the suspension. The drying procedures performed at 70 • C in the atmospheres of nitrogen and air let to the coalescence and growth of the nanoparticles, as well as some degradation has been noticed in some of the stabilizers.

Quantitative Analysis of Superparamagnetic Contrast Agent in Sentinel Lymph Nodes Using Ex Vivo Vibrating Sample Magnetometry

“…For the average particle size distribution further used for lymph node quantification, the following parameters were found: D 1 = 4.5 nm, σ 1 = 0.47, D 2 = 8.3 nm, σ 1 = 0.29, and p = 0.52. These values are in the same range as was found using a unimodal log-normal distribution for TEM analysis of Endorem nanoparticles [39], [48], [49]. The bimodal core size distribution has a more broadened peak compared to a unimodal log-normal distribution, but does not show two clear separate maximums.…”

Selective detection of magnetic nanoparticles in biomedical applications using differential magnetometry

“…Therefore, the measurement of the dm/dH-curve can be used to characterize magnetic nanoparticles behavior in alternating fields and to determine optimal parameters for Diffmag measurements. The particle size distributions fitted for the suspensions with Resovist and Endorem were in agreement with other studies [15,[24][25][26][27]32,33].…”

Sentinel lymph node identification with magnetic nanoparticles

“…For the average particle size distribution further used for lymph node quantification, the following parameters were found: ‫ܦ‬ ଵ = 4.5 nm, ߪ ଵ = 0.47, ‫ܦ‬ ଶ = 8.3 nm, ߪ ଵ = 0.29, ‫‬ = 0.52. These values are in the same range as was found using a unimodal lognormal distribution for TEM analysis of Endorem nanoparticles [39, 48,49]. The bimodal core size distribution has a more broadened peak compared to a unimodal lognormal distribution, but does not show two clear separate maximums.…”